Amid extraordinary moves to rein in criticism at home, Chinese security personnel are reaching confidently across borders, targeting Chinese and foreign citizens who dare to challenge the Communist Party line, in what one Western diplomat has called the “worst crackdown since Tiananmen Square.”

A string of incidents, including abductions from Thailand and Hong Kong, forced repatriations and the televised “confessions” of two Swedish citizens, has crossed a new red line, according to diplomats in Beijing. Yet many foreign governments seem unwilling or unable to intervene, their public response limited to mild protests.

The European Union is divided and appears uncertain about what to do. Hong Kong is in an uproar, with free speech under attack, activists looking over their shoulders and many people saying they feel betrayed by a lack of support from Britain.

Chinese state broadcaster CCTV in Beijing on Jan. 17 showed
Gui Minhai, a Swedish national and co-owner of a Hong Kong
publishing house, weeping. Gui went missing late last year.
(CCTV/AFP/Getty Images)

“China seems bent upon broadcasting to the world its disdain for the rule of law,” said Jerome A. Cohen, a China legal scholar and professor at New York University.

With Secretary of State John F. Kerry in Beijing, where he landed late Tuesday, the leaders of the Congressional-Executive Commission on China, an independent U.S. government agency, have voiced alarm. The body’s chairman, Rep. Christopher H. Smith (R-N.J.), said Friday that President Xi Jinping’s push toward “hard authoritarianism” threatens U.S.-China ties, a view echoed by his co-chairman, Sen. Marco Rubio (R-Fla.).

“On Xi’s watch, Hong Kong’s autonomy is under threat, and Beijing’s reach is ever-expanding to include foreign soil and foreign nationals living, working and doing business in China,” said Rubio, a presidential candidate. “President Xi is ruling by fear, not by the rule of law.”

Before this became a story about cross-border abductions, televised confessions and China’s long, throttling reach, it was a story about a book — a gossipy work on Xi’s love life. The book, which has not been published, is said to allude to the alleged girlfriends the president had before he took office.

It was to have been issued in the semiautonomous Chinese city of Hong Kong by a small publishing house, Mighty Current Media, whose name seems to foreshadow the rush of abductions by Chinese security forces that has swept up five men associated with the firm, including two foreign nationals.

On Oct. 17, Gui Minhai, a Hong Kong-based publisher and naturalized Swedish citizen, vanished from his 17th-floor vacation condominium in Thailand. Days later, three Mighty Current employees disappeared while visiting the Chinese city of Shenzhen.

In late December, Lee Bo, a British citizen, was apparently abducted from a warehouse in Hong Kong — an action that appeared to violate the “one country, two systems” principle Beijing pledged to uphold after taking control of the city from Britain in 1997. In a series of odd communications with his wife, Lee said he was “assisting with an investigation” in China and that “everything is fine.”

That proved unlikely. Months after Lee’s colleague Gui went missing, he reappeared on Chinese television last week to deliver a choreographed“confession” — for a car crash that took place in 2003.

Within the week, in an unrelated case, a second confession by a Swede was broadcast on state television. It featured Peter Dahlin, who has worked to support Chinese lawyers. He disappeared on his way to the Beijing airport on Jan. 3 and was held for nearly two weeks before being given access to consular officials. He was finally released Monday evening and deported, colleagues said.

A Chinese journalist, two dissidents and the son of a jailed civil rights lawyer also have gone missing or been forcibly repatriated from Thailand and Burma in the past three months, heightening the perception that for critics of the Chinese Communist Party and their families, nowhere is safe.

The U.S. State Department expressed “concern” about the confessions and the use of “extra-legal means” to bring foreign nationals to China. And the German Foreign Ministry voiced “really serious” concern that Britain and Sweden had either not been granted access to their citizens or were granted access only after an “unacceptable delay.”

“This is clearly and undoubtedly not in accordance with the international obligations of the People’s Republic of China with regard to the Vienna Conventions,” spokesman Martin Shaefer said Friday, referring to a 1963 international accord on consular relations.

But the response from other European countries has been anemic, say critics who note that many are keen to court Chinese investment.

When the European Union issued a statement calling on Chinese authorities to “review their decision” to expel a French journalist at the end of last year, many European embassies in Beijing declined to even publish the comment on their websites.

The Global Times, a nationalist Chinese newspaper published in Beijing,argued that the “mild response” from France and the European Union proved that the Chinese were right to throw the reporter out.

Many European nations also have not republished E.U. statements on the abductions of the booksellers and the arrest of Dahlin. China, critics say, has realized that Europe is weak and divided.

“The international reaction, from the E.U. in particular, should be a lot stronger than this — otherwise they will get more cases,” said Nicholas Bequelin, East Asia director for Amnesty International. “China has seen through the hypocrisy of Western countries with respect to human rights.”

On a visit to Beijing this month, British Foreign Secretary Philip Hammondwarned that if Lee had been abducted, it would represent an “egregious breach” of promises made in 1997. But Hammond also played down such reports as “pure speculation.”

“Hong Kong people feel increasingly that Britain is not honoring its moral and legal obligation to Hong Kong,” said Anson Chan, who served as the territory’s top bureaucrat directly after the handover. “Britain is desperate to do business with China almost on any terms.”

China’s apparent disrespect for Hong Kong’s autonomy and Lee’s British passport is a threat to the hundreds of thousands of residents who hold foreign passports, Chan said.

“If tomorrow you say something that someone doesn’t like, will you be spirited away and taken to mainland China?” she said.

That fear may be precisely Beijing’s point.

It also may signal worry at home, experts said, citing concerns intensified by a stock-market collapse and economic slowdown.

“As the economy begins to slow down, the leadership anticipates that the popularity of Xi Jinping and the party will take a body blow,” said Willy Wo-Lap Lam, an expert in Chinese politics at the Chinese University of Hong Kong.

In the middle of last year, China began a campaign against illegal publications that could “poison the hearts and minds” of its youths. Among the targets: “reactionary” publications out of Hong Kong and Taiwan.

Mighty Current’s works appeared to strike a particular nerve, because the publication suggested that Xi’s Communist Party rivals are leaking gossip to undermine him, and because the salacious subject matter might shatter the aura of invincibility he has cultivated.

“The people around Xi Jinping are furiously creating a Mao Zedong-style personality cult around him,” Lam said. “The book published in Hong Kong would have made a dent in that.”